You can not use the internal webcam with this software. You actually have to disable the internal camera to use an external webcam with this software. Some people have experienced system lockup after an extended period of use at an event. This requires shutting the system and restarting. There are many choices of photo booth software available today. These are all supported with technical support. Of course they range in cost from under a $100 to over $1K.
If you want to stay with a webcam system then I would suggest www.sparkbooth.com. The cost is only $59 and the support is great. It is easy set up and use.
There is a FB group that most of us have moved to that you maybe interested in looking at.
http://www.facebook.com/groups/photobooth1/
I hope this helps.
Gerald